Black or African-American?

[Alex]

As used in the United States, "caucasian" simply refers to skin color not region of origin. In Europe "caucasian" refers to people from that region.

How the name for that region came be used as the descriptive term for white people is an interesting bit of racist science history. Without going into details, the term was used because that's where early 19th science though the skull features of northern Europeans would ultimately be traced.

But to a degree it is all moot since race doesn't exist in an objective sense and in general usage people aren't at all rigorous in distinguishing race, ethnicity, and nationality. Or even the order in which they are important (the idea that the third of those should be primary is a relatively recent concept).